A known configuration of a supporting structure that supports a cylinder head cover with a cylinder head makes use of joining between a fastening member attached to the cylinder head and a damping member attached to the cylinder head cover. The fastening member may be, for example, a male screw member that engages, via a screw thread, with a female screw section formed in the cylinder head, whereas the damping member may be, for example, an elastic ring fitted into a fitting groove formed in the cylinder head cover. Further, as a result of the head of the male screw member being fitted into a fitting hole formed in the elastic ring, the cylinder head and the cylinder head cover are indirectly joined with each other (see Patent Document 1, for example).
Among fastening members that can be attached to a cylinder head, attention is paid to a fastener that is made of resin and has locking pieces obtained by cutting out some portions of a male screw section of a male screw member along the axial direction, for the purpose of reducing the labor required by the fastening process. Unlike the male screw section, the locking pieces formed on the fastener made of resin are able to warp along the axial direction. Accordingly, the operation of fastening the resin fastener is sufficiently accomplished by inserting the resin fastener into a hole having a female screw section, instead of rotating the resin fastener (see Patent Document 2, for example).